1. Field of the Invention
This invention relates to novel secalonic acid derivatives and methods for the preparation thereof.
2. Description of the Prior Art
Seven stereoisomers of secalonic acid such as secalonic acids A, B, C, D, E, F and G have been isolated from fungi or Lichenes and reported by the following literature.
(1) Isolation of secalonic acids A, B and C from Claviceps purpurea (B. Frank and E. M. Gottshalk, Angew. Chem. Internat. Edn., 1964, 3, 441; B. Frank, E. M. Gottshalk, U. Ohnsorge and F. Huper, Chem. Ber., 1966, 99, 3842; D. J. Abehart, Y. S. Chen, P. de Mayo and J. B. Stothers, Tetrahedron, 1965, 21, 1417). PA0 (2) Isolation of secalonic acids A and B from Penicillium islandicum (J. W. Apsimon, J. A. Corran, N. G. Greasey, W. Marlow, W. B. Whalley and K. Y. Sim, J. Chem. Soc., 1965, 4144). PA0 (3) Isolation of secalonic acid A from Parmelia entotheiochroa (I. Yoshioka, T. Nakanishi, S. Izumi and I. Kitagawa, Chem. Pharm. Bull., 1968, 16, 2090). PA0 (4) Isolation of secalonic acid D from Penicillium oxalicum (P. W. Steyn Tetrahedron, 1970, 26, 51). PA0 (5) Isolation of secalonic acid A from Aspergillus ochraceus (M. Yamazaki, Y. Maebayashi and K. Miyaki, Chem. Pharm. Bull., 1971, 19, 199). PA0 (6) Isolation of secalonic acid C from Cetraria ornata (I. Yoshioka, H. Yamauchi, K. Murata and I. Kitagawa, Chem. Pharm. Bull., 1972, 20, 1082). PA0 (7) Isolation of secalonic acid A, E and G from Pyrenochaeta terrestris (C. C. Howard, R. A. W. Johnstone and I. D. Entwistle, J. Chem. Soc. Comm., 1973, 464; C. C. Howard and R. A. W. Johnstone, J. Chem. Soc. Perkin I, 1973, 2440; I. Kurobane, L. C. Vining and A. G. McInnes, Tetrahedron Letters, in press). PA0 (8) Isolation of secalonic acids D and F from Aspergillus aculeatus (R. Andersen, G. Buchi, B. Kobbe and A. L. Demain, J. Org. Chem. 1977, 42, 352).
These secalonic acids are effective for an ascites carcinoma of mice and rats, however, they have such a drawback that they show a strong toxicity.